Stratagene Cloning Systems has initiated development of a shuttle vector system for the detection and characterization of chemical induced mutations in transgenic mice. Mouse strains have been developed with an integrated bacteriophage Lambda genome containing target genes that permit rapid detection of mutations. We propose several modifications of this integrated lambda vector which will allow rapid DNA sequence analysis of mutations within the target gene (lac I repressor gene). After exposure to a mutagen, DNA samples are prepared from mouse tissues. Phage DNA is recovered directly from the mouse genomic DNA utilizing Strategene's lambda packaging extracts. After plating, phage containing mutations within the target are easily identified by color assay. Next, the mutant target gene is automatically excised from the lambda phage and converted into a plasmid utilizing specific sites in the lambda phage and replication proteins derived from the bacteria phage M13. We have termed the class of vectors incorporating this conversion process lambda ZAP. The new mutagenic test vector will be constructed and then microinjected into mouse embryos. Mouse strains containing this novel shuttle vector will be used for rapid, detailed in vivo analysis of suspected chemical mutagens.